CIO A.H. Estahrook 



i?, NaCl solution for 24 hours, then for a like period into -f^ , then 

 into ^^ where they will now live and multiply. 



Fifty Paramecia were put into hay infusion and 50 into 1^ NaCl 

 in the same hay infusion. At the end of 24 hours, 50 of the con- 

 trol were put into fresh hay infusion, and 50 of those in the /« 

 NaCl were put into ^^^ NaCl. At the end of the 24 hours, there 

 were, as the result of some division, 69 in the control culture, 64 

 in the salt. Forty-four of the control were put into fresh hay 

 infusion, and the 64 in the salt were transferred to the ^^ NaCl. 

 At the end of 48 hours, the control numbered 54; those in j\ NaCl, 

 75. Fifty of each were killed and measured. The average meas- 

 urements of the 50 controls were 188.7 X 64.8 microns, of the 50 

 in 1^ NaCl, 170.7 X 70.02 microns. The Paramecia in the salt, 

 as well as those in the control, were large and active. There was 

 plenty of bacterial food present in both, the only evident difference 

 being the smaller size of those in the NaCl. After four days, 

 the specimens in the salt solution stopped dividing, while some 

 had divided in an abnormal way. In many the division was in- 

 complete, so that two specimens remained connected. Nothing 

 of the sort was seen in the controls, the latter continued to divide 

 normally. After the Paramecia had been in the i\ NaCl 6 days, 

 many began to die. An attempt was made to save these by put- 

 ting them into fresh hay infusion containing i^'oNaCl, but when a 

 few were introduced into this from the old culture, they all died 

 in one to two hours, while those remaining in the old ro NaCl 

 solution continued to live for nearly 20 hours more. The controls 

 remained normal and alive. 



Thus it is easy to acclimatize Paramecia to ^^ NaCl for a short 

 period, but it is more difficult to get them into perfect relation to 

 their changed environment. The animals in the salt at the latter 

 end of the experiment were evidently in a very unstable equilib- 

 rium with their environment. Possibly the effect was caused by 

 the accumulation of the sodium chloride in the cells. 



Summarizing the work with sodium chloride, we find that the 

 addition to the culture medium of sufficient NaCl to make a ^^ 

 or #0 solution permits the young specimens to grow for a few min- 

 utes after fission, then inhibits growth, finally causing death. 



